From its origins on the Kaffa plateau in Ethiopia, thecoffee plantspread first to the Yemen and then to most of the countries with a hot wet climate lying between the two tropics. It is this area of the world that produces green coffee, which has different properties depending on where it comes from (Brazil, Costa Rica, Jamaica, Ethiopia, etc.).
There are two botanical coffee species which have commercial value and are grown as crops: the Coffea Arabica and the Coffea Robusta.
Not only do they look different, but they taste and smell different and have completely different organoleptic characteristics.

Not only do they look different, but they taste and smell different and have completely different organoleptic characteristics.

But it is theroasting which completely changes the appearance and quality of the coffee. This is what gives the beans the appearance we are accustomed to see. During roasting, the bean opens and the central groove widens; it loses some 18-20% of its weight but increases in volume by 60%. It gradually changes colour, but above all undergoes relatively complex physicochemical reactions.
The degree of roasting depends on consumer taste and the region for which it is intended: a roast for the South of Italy is different from a roast for the North.
No machine or computer can replace the eye and intelligence of the expert coffee roaster.
The degree of roasting is the basis of any blend: Arabica beans always require a lighter roast to retain the delicate aromas which distinguish them, while Robusta beans need a darker roast to cover their woody characteristics.